Engineered Nanocrystallites for Enhanced Performance of Ceramic Coatings by Ion Beam Assisted Deposition

1996 ◽  
Vol 438 ◽  
Author(s):  
F. Namavar ◽  
J. Haupt ◽  
E. Tobin ◽  
H. Karimy ◽  
J. Trogolo ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Grain Size ◽  
High Temperature ◽  
Low Temperatures ◽  
Ion Beam ◽  
Film Deposition ◽  
Tin Films ◽  
Grain Sizes ◽  
Ion Beam Assisted Deposition

AbstractTypical high-temperature thin-film deposition techniques are not suitable for certain substrates such as polymers and thermally-sensitive steels. In this work, ion beam assisted deposition (IBAD) was used to deposit ceramic and metallic films at temperatures below 150°C with nanocrystalline (< 100Å diameter) grain size. Nanoindentation studies of these films have shown hardnesses 50 to 100% greater than larger-grained films and, in some cases, fracture toughness approaching that of Si3N4.By combining chromium evaporation with nitrogen beam bombardment, hard, adherent CrN films without any porosity have been produced at low temperatures with a N/Cr arrival ratio of about 1. The grain size is typically smaller than 100Å and hardness is typically higher than 25 GPa. For a N/Cr arrival ratio slightly less than 1, we observed possible grain boundary porosity. However, even with porosity, hardness is typically 20 to 24 GPa for grain sizes smaller than 100Å. For a N/Cr arrival ratio of 1/4 we deposited elemental Cr with a grain size of 300 to 500Å and a hardness greater than that of silicon (12 GPa). Using Ar ions and a N backfill, we produced elemental Cr containing a mixture of coarse (120 to 150Å) and fine (25 to 30Å) grains. For high-temperature deposition of CrN, the grain size increases (200 to 600Å) with a noticeable decrease in hardness. Mechanical properties of CrN are greatly influenced by impurities, as well as by surface conditioning of the substrate.TiN films having gold color and grain sizes from 50 to 1000Å have been produced at low temperatures. Nanoindentation measurements of hardness and fracture toughness indicate that impurity-free TiN (with grains smaller than 100Å) has a hardness higher than 25 GPa and a fracture toughness close to that of Si3N4, but with higher wear resistance. Mechanical properties of our TiN films are greatly influenced by impurities, particularly oxygen, although it does not influence the gold color of TiN.

Mechanical Properties of Nanocomposite TiN/Si3N4 Films Synthesized by Ion Beam Assisted Deposition (IBAD)

2003 ◽  
Vol 125 (2) ◽  
pp. 445-447 ◽  
Author(s):  
Chenhui Zhang ◽  
Jianbin Luo ◽  
Wenzhi Li ◽  
Darong Chen
Keyword(s):  
Mechanical Properties ◽  
Grain Size ◽  
Ion Beam ◽  
Nanocomposite Coatings ◽  
Ion Beam Assisted Deposition ◽  
Aisi 52100 ◽  
Aisi 52100 Steel ◽  
Nanoindentation Hardness ◽  
Si3n4 Film ◽  
Amorphous Si3n4

Nanocomposite coatings of TiN/Si3N4 have been prepared by ion beam assisted deposition (IBAD): simultaneous sputtering of Ti and Si targets and film bombardment by N2+ ions at 1000 eV. The Si/Ti ratio in the film varies from 0 to 0.9. The coatings are composed of amorphous Si3N4 and TiN nanocrystals with grain size of several nanometers. Such nanocomposites exhibit improved mechanical properties in comparison with TiN or Si3N4 deposited under the same conditions. The nanoindentation hardness of TiN/Si3N4 film at the Si/Ti ratio of 0.3 reaches a maximum of 42 GPa, compared with 22 GPa for TiN and 18 GPa for Si3N4. The wear resistance of AISI 52100 steel coated with these nanocomposite coatings is increased about three times.

Microstructure and Mechanical Properties of C/SiC Composites Prepared at Low Temperatures

2008 ◽  
Vol 368-372 ◽  
pp. 849-851
Author(s):  
Chang Cheng Zhou ◽  
Chang Rui Zhang ◽  
Hai Feng Hu ◽  
Yu Di Zhang ◽  
Zhi Yi Wang
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Fracture Toughness ◽  
Shear Strength ◽  
High Temperature ◽  
Low Temperatures ◽  
High Performance ◽  
Microstructure And Mechanical Properties ◽  
Potential Applications ◽  
Sic Composites

2D-C/SiC composites with high performance were prepared at temperatures as low as 900 °C. The flexural strength of the composites reached 329.61MPa, the same level as the composites prepared at 1200°C, and shear strength and fracture toughness were 32.14MPa and 14.65MPa·m1/2, respectively. The microstructure and mechanical properties of the composites after heat-treatment at 1600°C were also investigated to determine the potential applications at high temperature.

Mechanical Properties and Microstructure of Partially Sintered Zirconia Ceramics

2008 ◽  
Vol 368-372 ◽  
pp. 1252-1254 ◽  
Author(s):  
Shi Bao Li ◽  
Zhao Hui Chen ◽  
Yi Min Zhao ◽  
Zhong Yi Wang ◽  
Li Hui Tang ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Grain Size ◽  
Bending Strength ◽  
Target Material ◽  
Dental Restoration ◽  
Diameter Distribution ◽  
Zirconia Ceramics ◽  
Grain Sizes ◽  
Cad Cam

Partially sintered zirconia ceramics (PSZCs) for dental uses were prepared from zirconia nanopowder via isostatic pressing and partially sintering. The open porosities, pore diameters, grain sizes and mechanical properties of the ceramics with different densities were studied. The results show that the pores formed in the PSZCs are all open pores, with a diameter distribution of 60nm~130nm and a grain size distribution of 120~170nm. The machinability becomes worse when the density of PSZC is higher than 75% of the theoretical density, so a ceramic named PSZC-70% with density of 70%TD was selected as the target material. Its bending strength is 168 MPa and fracture toughness is 1.8 MPa·m1/2. A dental restoration framework can be obtained via machining the PSZC-70% on a dental CAD/CAM system.

AL TECH POTOMAC A

Alloy Digest ◽  
1987 ◽  
Vol 36 (7) ◽  
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
High Temperature ◽  
Tensile Ductility ◽  
Heat Treating ◽  
Fatigue Properties ◽  
Die Steel ◽  
Transverse Tensile ◽  
Temperature Performance ◽  
Specialty Steel

Abstract AL TECH POTOMAC A has well-balanced strength and toughness which make it especially suitable for a wide variety of hot-die steel applications, including those involving severe coolants. Its outstanding mechanical properties make it useful for many non-tooling requirements such as aerospace components. For more specialized needs, the manufacturer offers special melting processes that enhance this steel's fatigue properties and transverse tensile ductility. This datasheet provides information on composition, physical properties, microstructure, hardness, elasticity, and tensile properties as well as fracture toughness. It also includes information on high temperature performance as well as forming, heat treating, and machining. Filing Code: TS-478. Producer or source: AL Tech Specialty Steel Corporation.

Mechanical Properties of Electroplated Copper Thin Films

1999 ◽  
Vol 594 ◽  
Author(s):  
R. Spolenak ◽  
C. A. Volkert ◽  
K. Takahashi ◽  
S. Fiorillo ◽  
J. Miner ◽  
...  
Keyword(s):  
Thin Films ◽  
Mechanical Properties ◽  
Grain Size ◽  
Film Thickness ◽  
Yield Stress ◽  
Laser Scanning ◽  
Focused Ion Beam ◽  
Ion Beam ◽  
Cu Films ◽  
Electroplated Copper

AbstractIt is well known that the mechanical properties of thin films depend critically on film thickness However, the contributions from film thickness and grain size are difficult to separate, because they typically scale with each other. In one study by Venkatraman and Bravman, Al films, which were thinned using anodic oxidation to reduce film thickness without changing grain size, showed a clear increase in yield stress with decreasing film thickness.We have performed a similar study on both electroplated and sputtered Cu films by using chemical-mechanical polishing (CMP) to reduce the film thickness without changing the grain size. Stress-temperature curves were measured for both the electroplated and sputtered Cu films with thicknesses between 0.1 and 1.8 microns using a laser scanning wafer curvature technique. The yield stress at room temperature was found to increase with decreasing film thickness for both sets of samples. The sputtered films, however, showed higher yield stresses in comparison to the electroplated films. Most of these differences can be attributed to the different microstructures of the films, which were determined by focused ion beam (FIB) microscopy and x-ray diffraction.

scholarly journals Is Superplasticity in the Future of Nanophase Materials?

1990 ◽  
Vol 196 ◽  
Author(s):  
R. W. Siegel
Keyword(s):  
Mechanical Properties ◽  
Grain Size ◽  
Room Temperature ◽  
Grain Boundary Sliding ◽  
Atomic Clusters ◽  
Diffusional Creep ◽  
Ultrafine Grain ◽  
Grain Sizes ◽  
Nanophase Materials ◽  
Boundary Sliding

ABSTRACTThe ultrafine grain sizes and high diffusivities in nanophase materials assembled from atomic clusters suggest that these materials may have a strong tendency toward superplastic mechanical behavior. Both small grain size and enhanced diffusivity can be expected to lead to increased diffusional creep rates as well as to a significantly greater propensity for grain boundary sliding. Recent mechanical properties measurements at room temperature on nanophase Cu, Pd, and TiO2, however, give no indications of superplasticity. Nonetheless, significant ductility has been clearly demonstrated in these studies of both nanophase ceramics and metals. The synthesis of cluster-assembled nanophase materials is described and the salient features of what is known of their structure and mechanical properties is reviewed. Finally, the answer to the question posed in the title is addressed.

Effect of Microcast-X Fine Grain Casting on the Microstructure and Mechanical Properties of K492M Alloy at 760°C

2016 ◽  
Vol 849 ◽  
pp. 549-556
Author(s):  
Pin Pin Hu ◽  
Qi Dong Gai ◽  
Qing Li ◽  
Xin Tang
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Grain Size ◽  
Rupture Life ◽  
Stress Rupture ◽  
Casting Alloy ◽  
Stress Rupture Life ◽  
Casting Technique ◽  
Conventional Casting ◽  
Fine Grain

The effect of Microcast-X fine grain casting on the microstructure and mechnical property K492M alloy at 760°C of was investigated. The results indicated that Microcast-X fine grain casting decreased grain size and dendrite space of γ′ phase and γ/γ′ eutectic. In addition, the element segregation decreased significantly compared to conventional casting technique. Also, the size and distribution of MC carbide were improved. By Microcast-X fine grain casting, the tensile strength increased from 934MPa of conventional casting alloy to 1089MPa and the elongation increased from 1.9% to 5.7%. In addition, the stress-rupture life increased from 28.8h of conventional casting alloy to 72.5h. And the fracture mechanism for the alloys by Microcast-X fine grain casting is trans-granular fracture toughness.

Simulation of the interaction of plastic zone dislocations with the grain boundary at brittle-plastic transition temperatures in molybdenum

2021 ◽  
Vol 2021 (3) ◽  
pp. 77-85
Author(s):  
K. M. Borysovska ◽  
◽  
N. M. Marchenko ◽  
Yu. M. Podrezov ◽  
S. O. Firstov ◽  
...  
Keyword(s):  
Fracture Toughness ◽  
Grain Size ◽  
Grain Boundary ◽  
Plastic Zone ◽  
Grain Boundaries ◽  
Crack Tip ◽  
Dynamics Simulation ◽  
Density Of Dislocations ◽  
Grain Sizes ◽  
Pile Up

The (DD) method was used to model the formation of the plastic zone of the top of the cracks in polycrystalline molybdenum. Special attention was paid to take into account the interaction of dislocations in the plastic zone with grain boundaries. Structural sensitivity of fracture toughness was analyzed under brittle-ductile condition. Simulations were performed for a range of grain sizes from 400 to 100 μm, at which a sudden increase in fracture toughness with a decrease of grain size was experimentally shown. We calculated the value of K1c taking into account the shielding action of dislocations. The position of all dislocations in the plastic zone at fracture moment was calculated. Based on these data, we obtained the dependences of dislocation density on the distance from the crack tip thereby confirming significant influence of the grain boundaries on plastic zone formation. At large grain sizes, when the plastic zone does not touch the boundary, the distribution of dislocations remained unchanged. As grains reduce their size to size of the plastic zone, they start formating a dislocation pile – up near the boundaries. Dislocations on plastic zone move slightly toward the crack tip, but the density of dislocations in the middle of the grain remains unchanged, and fracture toughness remains almost unchanged. Further reduction of the grain size leads to the Frank-Reed source activation on the grain boundary Forming dislocation pile-up of the neighbor grains. Its stress concentration acts on dislocations of the first grain and causes redistribution of plastic zone dislocations. If the reduction in grain size is not enough to form a strong pile-up, density of dislocations on plastic zone increases slightly and crack resistance increases a few percent. Further reduction of grains promotes strong pile-up, dislocations move to crack tip, and its density on plastic zone increases. Crack is shielded and fracture toughness increases sharply. The calculation showed that the fracture toughness jump is observed at grain sizes of 100—150 μm, in good agreement with the experiment. Keywords: dislocation dynamics simulation, molybdenum, fracture toughness, grain size, plastic zone, brittle-ductile transition.

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